Did I miss a spoiler about Gabi and Nick separating or divorcing? Otherwise it makes no sense for Gabi to move in with Will or vice versa.

Not yet. We've only got as far as Nick, Gabi, Sonny and Will getting kidnapped. Will getting shot after saving Gabi. No real news on the aftermath yet. I'm guessing, if Gabi has a lick of sense, she will leave Nick after she finds out he's being keeping so many secrets from her.